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Multi-Way Conventional loudspeakers with crossovers

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Old 8th January 2018, 03:30 AM   #21
LineSource is offline LineSource  United States
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Quote:
Originally Posted by Xerxes75 View Post
So a few weeks ago I decided to build the SB18 which is more budget friendly. I don't have the time yet, I am curious about the results! R.
You will find a few diy designs using the SB17NRXC35-8 and SB29RDC-4 tweeter. Some are optimized for flat baffle cabinets of various internal volume and bass port tuning. Some crossovers are optimized for a time-stepped baffle. Some crossovers are optimized for a slanted baffle used to create a triangular T-M time alignment at the listener. In the USA designs which fit a common ready-built cabinet from Parts Express are popular.

Lower cost SB26STAC tweeter:
SB Acoustics :: Eka Kit
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Old 8th January 2018, 07:12 PM   #22
Xerxes75 is offline Xerxes75  Netherlands
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Thanks for your suggestions. I see a lot of different designs with the SB17NRXC35-8. The EKA ket looks very good. Today a pair of SB26STAC came up for sale for half the price... and hope to get them..
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Old 12th January 2018, 05:11 PM   #23
Xerxes75 is offline Xerxes75  Netherlands
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Originally Posted by Xerxes75 View Post
Thanks for your suggestions. I see a lot of different designs with the SB17NRXC35-8. The EKA ket looks very good. Today a pair of SB26STAC came up for sale for half the price... and hope to get them..
I have scored them (SB26STAC), while I was searching for a pair of SB17NRXC35-8 I came across a pair of satori mw16p-8 but I don't if they pair up...

R.
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Old 20th January 2018, 10:37 PM   #24
Roo2 is offline Roo2  Australia
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Hello there,
I'm having a few challenges reconciling my crossover design. I'm using Linesource's posts above to check my calcs.
The 3rd order Butterworth calculations I do using the cookbook formulas and online calculators result in series lower inductor values in the low pass than both the above designs.
BW3 Crossover fx (Hz) Tweet R ohm Woof R ohm
1700 6 8
C1 10.40uH
C2 31.21uH
C3 15.60uH
L1 0.42 mH
L2 1.12 mH
L3 0.37 mH
Is baffle edge correction significantly increasing series inductor sizes in the two designs posted by Linesource above?
Also, I get different L-pad resistance results. I calculate similar parallel resistor values but lower series resistance values...
eg for 3dB attenuation of my 6 ohm tweeter I calculate 1.8 ohms series R, 14.5 ohms //R. What am I not taking into account?
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Old 21st January 2018, 04:04 AM   #25
PeteMcK is online now PeteMcK
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are you using actual impedance values, or nominal?
Online calculators are OK, but they need a bit of knowledge to get good results
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Impedance varies with frequency, use impedance plots of your drivers and make crossover calculations using the actual impedance of the driver at the crossover frequency
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Old 21st January 2018, 06:32 AM   #26
Roo2 is offline Roo2  Australia
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Nominal Pete. 6ohm tweeter, 8ohm woofer. The online calculators give me the same results as the loudspeaker cookbook formulas. I wanted to understand Linesources design from post #11 better. Especially the L-pad and the baffle edge correction.

Last edited by Roo2; 21st January 2018 at 06:43 AM.
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Old 31st January 2018, 09:45 AM   #27
Xerxes75 is offline Xerxes75  Netherlands
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Hi Roo2,

How is project doing?
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Old 31st January 2018, 11:11 PM   #28
Roo2 is offline Roo2  Australia
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Hi Xerxes75. Slowly�� I’ve been busy at work and at home. I’m also stuck on the crossover. Particularly the low pass. There are a couple of designs above for the SB17 that don’t reconcile with my simple calcs and understanding and I don’t want to throw money into buying and trying lots of inductors and capacitors.
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Old 1st February 2018, 07:52 AM   #29
giralfino is offline giralfino  Italy
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Quote:
I'm having a few challenges reconciling my crossover design. I'm using Linesource's posts above to check my calcs.
The 3rd order Butterworth calculations I do using the cookbook formulas and online calculators result in series lower inductor values in the low pass than both the above designs.
I haven't checked your specific case, but this should be because crossover calculators omit the baffle step effect. If you build a LP filter using simply a textbook crossover you'll end up with tiny bass, as this will be 6dB down from midrange/high. Baffle step correction is usually performed with "oversized" coils.

Quote:
Also, I get different L-pad resistance results. I calculate similar parallel resistor values but lower series resistance values...
eg for 3dB attenuation of my 6 ohm tweeter I calculate 1.8 ohms series R, 14.5 ohms //R. What am I not taking into account?
Again, this is a side effect of a baffle step compensation. You have to pad down the tweeter more than you expected, up to 6dB more.

Ralf
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Old 1st February 2018, 08:42 AM   #30
Roo2 is offline Roo2  Australia
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Thanks giralfino. Yes, the baffle step correction is where I seem to becoming unstuck. It's tempting to go with Linesources design on page 2 (post #11) which appears to cover it all but I like to understand stuff a bit before I buy It would be excellent to understand that design better.
Last week I also went through AllenB's tutorial sticky: Introduction to designing crossovers without measurement
It's a simpler approach with lower parts count (2nd order?) but doesn't appear to end up with the oversized coil, baffle step correction that sounds like a good thing to have.
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